DESCRIPTION: (Applicant's Abstract) Many efforts to improve substance abuse treatment services rely on the accurate measurement of treatment outcomes. The Addiction Severity Index (ASI), a structured interview often conducted over the telephone at follow-up, is frequently used by both clinicians and researchers to assess the effectiveness of treatment in a number of areas, including substance use. Although the ASI has been shown to be valid in most treatment settings and populations, there have been concerns about the accuracy of self-reports of substance use in other contexts. Among cocaine abusers in particular, there is evidence that self-reports may substantially understate the level of drug use. In one cocaine treatment outcome study at the proposed project site, underreporting on the ASI was more common among those who had received little or no treatment than it was among treatment completers. Thus, those with little or no treatment may give the impression of having improved nearly as much as completers, which could lead to a considerable underestimation of treatment service effectiveness in outcome studies of cocaine abusers. The present 3-year project will investigate the accuracy of ASI self-reports in a population of cocaine abusers, and test means of improving the validity of those self-reports. It will cross three factors to determine: (A) whether in-person and telephone ASI interviews yield responses of equal validity (the methods have apparently not been compared on a large scale before); (B) whether warning respondents that they will be asked for a urine specimen and hair sample increases self-report validity; and (C) whether some changes in the ASI's wording will improve the accuracy of self-reports. Subjects will be 595 cocaine abusers interviewed six months after their admission to a three-month treatment program. The principal goal of the proposed study is to define ways in which self-reports of substance use on the ASI at follow-up could be made more accurate. The results should benefit treatment programs, clinicians and researchers involved in assessing treatment outcomes.